The invention concerns a chock in a rolling stand for receiving a roll neck with a neck lining of a roll used in steel and nonferrous metal processing, where the chock has a roll body side that faces the roll and a discharge side that lies on the opposite side from the roll body side, with lubricant receiving chambers on the roll body side.
Roll neck bearings, especially Morgoil roll neck bearings, have been used for decades in rolling mill construction. In this regard, all load-carrying bearing parts, including the mounting elements and seals, are housed in a bearing housing, the so-called chock.
Neck linings are mounted on the journal of the rolls, i.e., the roll neck. Together with the bearing bush, the neck linings form a journal bearing, with the bearing bush being fixed in the chock. In this connection, the bearing bush encloses the neck lining.
Between the outer surface of the neck lining and the inner surface of the bearing bush, there is an oil film, which prevents metallic contact of the bearing linings. The oil is continuously forced through the bearing. This means that the oil is circulating. The oil enters the journal bearing through oil inlet pockets, which are located in the bearing bush and are supplied with oil from an oil reservoir through lines that are formed as bores in the chocks.
The constant pressure of the oil pumps forces the oil onto the bearing linings, where it spreads out. Excess oil emerges at the two lateral edges, where it is collected and returned to the oil reservoir through outlet lines.
To prevent oil from escaping from the bearings and getting onto the rolling stock, a seal is provided on the roll body side. A journal bearing can be sealed by a rubber profile produced by compression molding. The seal causes oil emerging from the bearing to enter cavities in the chock, from which it is further conveyed.
EP 0 285 333 B1 describes a bearing bush, which is divided into two pressure zones by an annular channel located in the bearing center. About 50% of the oil flowing off from the bearing is carried away through this annular channel. The sealing system on the roll body side is now loaded with only about half the usual amount of oil. The possibility of uncontrolled escape of oil is reduced.
In this connection, it is necessary to provide each of the two zones of the bearing bush with its own inlet, through which oil is supplied to the inner bearing surface. In addition, outlets are provided in the annular channel for removing the oil.
These additional measures result in increased manufacturing expense.
WO 2004/065 031 A1 discloses a chock for receiving the roll neck of a roll used in steel and nonferrous metal processing, comprising at least one lubricant receiving chamber on the roll body side and at least one lubricant receiving chamber on the discharge side, which are located beneath the lowest bearing point, and connecting bores between the lubricant receiving chambers on the roll body side and the discharge side, where, on the roll body side of the chock, the lubricant is collected in additional lubricant receiving chambers in the chock. The additional lubricant receiving chambers are located above or at the level of the center plane. This has the effect that the oil emerging at the top, above the center plane, is spared the long travel distance to the lowest bearing point and thus avoids interference by other emerging oil. In a chock, the lubricant, i.e., the oil, must be brought to the point at which the greatest pressure and the greatest friction between the roll neck and the chock occur. In the case of an upper chock, this point is always at the top, i.e., above the center plane, because the rolling force is upwardly directed and therefore the lubricant, i.e., the oil, is forced out of the bearing by the force and would have to move a long distance down to the lowest bearing point. There is a risk of oil escaping from the seal on its way to the bottom.
In the operation of a rolling mill, the function of the seal on the roll body side can be disrupted. For example, a rise of the oil in the collecting chamber in an oil sump can cause the sealing lip of the seal on the roll body side to leak. Another type of disruption involves wear of the sealing lips of a seal. The properties of the sealing lip change in a way that allows oil to escape. This results in oil leakage and large oil losses. In cold rolling mills, the escape of oil can cause fouling of the strip, which impairs the quality of the product.
In previously known chocks, the oil collected in collecting chambers on the roll body side is further conveyed by two bores that join the roll body side with the discharge side. The bores are located below the lowest bearing point. The oil flows through the bores to an oil collecting chamber on the outside of the chock. From there, the oil is carried by flexible hoses into the return line to the oil reservoir via one or two bore connections. The previously known bores are provided on the right and left in the chock (cf. FIG. 2 of WO 2004/065 031, lubricant receiving chambers 20 and 21, with the associated bores 10, or the bores 40 in FIGS. 4A, 4B of EP 0 285 333). In both embodiments, the horizontal distance between the oil return bores is greater than the diameter of the roll neck.
The prior-art arrangement and design of the lubricant return bores in this position means that the chocks cannot be altered in the lower region without shifting the lubricant return bores.